The present invention relates to a silver halide photographic material, and more particularly to a silver halide photographic material using a high-sensitivity sensitive silver halide photographic emulsion having high sensitivity in inherent absorption of the silver halide grains thereof, having small inherent desensitization also in addition of a sensitizing dye and also improved in spectral sensitivity.
When tabular silver halide grains are used in photographic materials, they are improved in spectral sensitization, sharpness, light scattering characteristics, covering power, development progress and granularity, compared with non-tabular silver halide grains. Accordingly, tabular grains having twin planes parallel to each other and having {111} faces as major faces have come to be variously used. For details thereof, reference can be made to the descriptions of JP-A-58-113926 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d), JP-A-58-113927, JP-A-58-113928, JP-A-2-828, JP-A-2-28638 and JP-A-2-298935. When sensitizing dyes are adsorbed in large amounts by silver halide grains, grains having {100} faces are usually better in color sensitivity characteristics. Recently, therefore, tabular silver halide grains having {100} faces as major faces have been developed. For details thereof, reference can be made to the description of JP-A-51-88017, JP-B-64-8323 (the term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d), JP-A-5-281640, JP-A-5-313273, JP-A-6-59360, JP-A-6-324446, JP-A-8-122954, JP-A-9-34045, JP-A-9-189977, EP-A-0534395, and U.S. Pat. Nos. 5,292,632, 5,314,798 and 5,264,337. However, tabular silver halide grains are known to deteriorate in pressure properties (pressure-induced fog and pressure-induced desensitization) Further, JP-A-6-43605 and JP-A-6-43606 disclose that when tabular grains high in aspect ratio are decreased to less than 0.1 xcexcm in thickness, light reflection characteristics thereof rapidly deteriorate.
Non-tabular grains having a thickness exceeding 0.3 xcexcm also find photographic applications in which advantages accrue because of their thickness. For example, it is proposed that they are used in a technique for complementing a light (for example, a blue light) in a spectral region in which a silver halide exhibits inherent sensitivity at its maximum. Examples thereof include a complement of an insufficient blue light of an artificial light source such as a tungsten filament lamp.
On the other hand, the influence of dislocation on photographic characteristics is described in G. C. Farnell, R. B. Flint and J. B. Chanter, J. Phot. Sci., 13, 25 (1965), which indicates that in tabular AgBr grains large in size and high in aspect ratio, places where latent image nuclei are formed and defects in the grains are in a close relation.
Techniques for introducing dislocation into normal crystal silver halide grains are described in JP-A-4-263246, JP-A-4-317050 and JP-A-4-348337. The dislocation-introduced normal crystal grains provide photographic materials high in sensitivity, excellent in granularity and sharpness, and moreover improved in pressure properties.
Techniques for utilizing dislocation (screw dislocation) for giving anisotropic growth to normal crystal grains are disclosed in JP-A-6-59360, JP-A-7-234470, JP-A-8-122954, JP-A-8-339044, JP-A-9-189977 and Japanese Patent Application No. 11-92883. In Japanese Patent Application No. 11-92883, it is described that in such a case, the number of dislocation lines is as small as 10 or less, but the photographic characteristics are sufficiently improved (the spectral sensitivity is increased, and the inherent desensitization is also reduced in addition of a sensitizing dye).
JP-A-63-220238, JP-A-1-201649, JP-A-2-127635, JP-A-3-237450, JP-A-4-191729 and JP-A-4-195035 disclose techniques for introducing dislocation into tabular silver halide grains having twin planes parallel to each other and having {111} faces as major faces. It is shown that the dislocation-introduced tabular grains are excellent in photographic characteristics such as sensitivity and reciprocity law, compared with grains having no dislocation, and that the use thereof in photographic materials results in excellent sharpness and granularity. As to sites where dislocation lines exist, peripheries, major faces, vertex portions or combinations thereof are described. However, grains in which dislocation lines are geometrically specified to twin planes have never known. Further, the number of dislocation lines is not less than 10, and no example has been known in which less than 10 dislocation lines improve the photographic characteristics.
It is therefore an object of the invention to provide a silver halide photographic material using a high-sensitivity sensitive silver halide photographic emulsion having high sensitivity in inherent absorption of silver halide grains thereof, having small inherent desensitization also in addition of a sensitizing dye and also improved in spectral sensitivity.
The object of the invention has been attained by the following silver halide photographic materials
(1) A silver halide photographic material comprising a support having provided thereon at least one layer of a light-sensitive silver halide emulsion, in which the emulsion comprises at least a dispersing medium and silver halide grains, and 50% or more of the total projected area of the silver halide grains is occupied by grains each having therein at least one twin plane and at least one dislocation line not parallel to the twin plane;
(2) The silver halide photographic material of (1), wherein the angle between the twin plane and the dislocation line is 30 degrees to 90 degrees;
(3) The silver halide photographic material of (1), wherein the angle between the twin plane and the dislocation line is 50 degrees to 90 degrees;
(4) The silver halide photographic material of (1), (2) or (3), wherein the number of the dislocation lines is from 1 to 10; and
(5) The silver halide photographic material of (1), (2), (3) or (4), wherein the amount of bromide contained in the silver halide grains is 50 mol % or more based on all the halides.